Oxygen consumption by purified plasmalemma vesicles from wheat roots

Abstract

Plasmalemma vesicles from wheat ( Triticum aestivum L.) roots consumed O 2 and the addition of 1 mM NADH increased the rate ~ 3‐fold (to 15‐30 nmol O 2 ·mg −1 ·min −1 ). The NADH‐dependent O 2 uptake was abolished by catalase. In the presence of salicylhydroxamic acid (SHAM), an inhibitor of the alternative oxidase pathway in plant mitochondria, NADH‐dependent O 2 consumption was stimulated 10–20‐fold (to 200–400 nmol·mg 1̄ ·min −1 ). Catalase also abolished this stimulation, which was KCN‐sensitive but antimycin A‐insensitive, and the production of H 2 O 2 during SHAM‐stimulated NADH‐dependent O 2 uptake was demonstrated. Irrespective of the mechanism, SHAM‐stimulated respiration by root plasmalemma makes it difficult to interpret results on root respiration obtained using KCN and SHAM.